Pressure-adjusting device for adjusting output of integrated pressure sensor

Abstract

A pressure-adjusting device for adjusting an output of an integrated pressure sensor in which a silicon wafer is joined onto a seat that has pressure-adjusting passages formed therein, and which has formed in the silicon wafer a signal processing circuit with an adjusting resistor for each chip, a thin diaphragm for each chip and a piezo-resistance layer for each chip. The pressure-adjusting device includes a pressure-setting stage on which the seat is placed, the pressure setting stage having pressure-adjusting passages formed therein to adjust a pressure exerted on the respective thin diaphragm via the pressure-adjusting passages formed in the seat. A holding member is arranged on the pressure-setting stage as to surround at least an outer periphery of the seat. A first elastic air-tight member is arranged on the pressure-setting stage as to surround the outer periphery of the seat and be held compressed by the pressure-setting stage and by the holding member. A second elastic air-tight member is arranged to surround the outer periphery on an upper surface of said silicon wafer or to surround the outer periphery of either the seat or the silicon wafer, and be held compressed by the seat or by the silicon wafer and the holding member.

We claim: 
     
       1. A pressure-adjusting device for adjusting an output of an integrated pressure sensor in which a silicon wafer is joined onto a seat that has pressure-adjusting passages formed therein, and which has formed in said silicon wafer a signal processing circuit with an adjusting resistor for each chip, a thin diaphragm for each chip and a piezo-resistance layer for each chip, said pressure-adjusting device comprising: a pressure-setting stage on which said seat having pressure adjusting passages is placed, said pressure setting stage having pressure-adjusting passages formed herein to adjust a pressure exerted on respective thin diaphragms via said pressure-adjusting passages formed in said seat;   a holding member which is so arranged on said pressure-setting stage as to surround at least an outer periphery of said seat;   a first elastic air-tight member which is so arranged on said pressure-setting stage as to surround the outer periphery of said seat and be held compressed by said pressure-setting stage and by said holding member; and   a second elastic air-tight member which is so arranged as to surround an outer periphery on an upper surface of said silicon wafer or to surround the outer periphery of at least either the seat or the silicon wafer, and be held compressed by the seat or by the silicon wafer and the holding member.   
     
     
       2. A pressure-adjusting device for adjusting an output of an integrated pressure sensor which forms in a silicon wafer a signal processing circuit with an adjusting resistor for each chip, a thin diaphragm for each chip and a piezo-resistance layer for each chip, said pressure-adjusting device comprising: a pressure setting stage on which is placed said silicon wafer or a seat to which said silicon wafer is joined, and which has pressure-adjusting passages formed therein to adjust a pressure exerted on respective thin diaphragms of said silicon wafer;   a holding member which air-tightly holds an outer periphery of said silicon wafer on said pressure-setting stage; and   a pressure-adjusting means that applies first and second negative pressures that are sufficient for bringing the silicon wafer or the seat into intimate contact with the pressure-setting stage, the first and second negative pressures being applied to said diaphragms of said silicon wafer via the pressure-adjusting passages formed in the stage in open atmosphere.   
     
     
       3. A pressure-adjusting device according to claim 2 wherein said first and second negative pressures are set at pressure levels, each level being sufficient for bringing the seat into intimate contact with the pressure-setting stage. 
     
     
       4. A pressure-adjusting device for adjusting an output of an integrated pressure sensor which forms on a silicon wafer a signal processing circuit with an adjusting resistor for each chip, a thin diaphragm for each chip and a piezo-resistance layer for each chip, said pressure-adjusting device comprising: a pressure-setting stage on which is placed said silicon wafer or a seat to which said silicon wafer is joined and which has pressure-adjusting passages formed therein to adjust a pressure that is exerted on respective thin diaphragms;   a groove formed in an upper surface of said pressure-setting stage so as to face said silicon wafer or a lower surface of an outer periphery of the seat yet surrounding an outer periphery of the silicon wafer or the seat;   a magnet secured in said groove; and   a magnetic fluid filled in said groove to maintain air-tightness between said pressure-setting stage and said silicon wafer or said seat.